1. Field of the Invention
The present invention relates to a control apparatus for an electronic musical instrument, and more particularly to a control technique for causing after-touch input data to reflect on musical tones generated by a sound source.
2. Description of the Related Art
Electronic musical instruments of a keyboard type have been mainly developed in the history of the development of electronic musical instruments. Inevitably, control apparatus (typically a micro-computer) for electronic musical instruments of a keyboard type have been seriously developed with a theme to be solved that a sound control can be performed suitably for a manipulator of a keyboard type instrument such as a keyboard, bender, modulation wheel, pedal and the like. In addition, communication technique, for example, MIDI (Musical Instrument Digital Interface) has been developed so as to be used suitably for electronic musical instruments of a keyboard type.
In recent times however, electronic musical instruments other than that of a keyboard type have been widely used, and particularly, electronic stringed instruments of a guitar type and electronic wind instruments of a reed type have been put into practice. Users of these instruments often connect various types of electronic musical instruments to each other, thereby playing those instruments, and wherein a wide variety of ways of expression of music have been proposed.
Unfortunately, an electronic musical instrument with a sound source capable of being connected to an external electronic musical instrument as a controller (a performance input apparatus) is constructed such that its control apparatus is suitably connected to a performance input apparatus of a keyboard type. Therefore, this electronic musical instrument can not be properly used with an arbitrary type of performance input apparatus. A method of playing a typical keyboard instrument and a method of playing a typical wind instrument are greatly different from each other and furthermore musical spaces which a player wants to express with these playing methods are quite different and the musical instruments respond in quite different ways depending on these playing methods. Needless to say, it is preferable in application of the electronic musical instruments that the essential difference in methods of playing the musical instruments causes the sound sources to respond in different ways and a performance effect is expressed as the player intended.
For instance, after-touch data of a keyboard type instrument is detected from key-depression pressure after key depression, while after-touch data of a wind instrument is given by output of a breath-sensor and/or lip-sensor. A control apparatus for a performance-input apparatus of a keyboard instrument serves to control to linearly change a musical-tone characteristic (for example, sound volume) in response to after-touch input. Meanwhile, the musical-tone characteristic is not always changed linearly in the wind musical instrument. More specifically, it is preferable that the sound volume may be linearly changed in response to change in after touch, when sensibility of a sensor is low, and when sensibility of the sensor is somewhat high, the sound volume is scarcely affected by a low value of after-touch data, and also when the sensibility of the sensor becomes of a certain value, the sound volume is greatly changed responding to a slight change in after-touch data. However, a conventional control apparatus for the keyboard instrument linearly changes a musical-tone characteristic in response to after-touch data input. Accordingly, when the above conventional control apparatus is used with an electronic wind instrument connected therewith as a performance input apparatus, a problem is left that performance expression shall be far from satisfaction of the instrument player. Since keyboard operation itself has only limited degree of freedom, a comparatively slow change in key depression is detected as after-touch data generated by keyboard operation. Therefore, the control apparatus for the keyboard instrument can provide after-touch effect without hindrance. Meanwhile, a breath controller of the wind instrument generates after-touch data which changes with a high degree of freedom in accordance with sensitive breath control by the instrument player. However, it shall be difficult to receive after-touch data from the breath controller as intended to obtain by the player and to process the data so as to control musical tones as expected, because of drawbacks in a digital system such as accuracy of a breath-detection element, the resolution of A/D converter, the accuracy of after-touch data which the control apparatus receives and processes. Particularly, while the player controls the air flow he supplies to the instrument to provide a constant breath flow, fractional variations in after-touch data are frequently caused. The fractional variations in data directly reflect on control data for after-touch effect and whereby variations of characteristic of musical tones are frequently repeated. As a result, there is left a problem that unnatural sounds are generated (a limit cyclic problem).
A speed at which after-touch data are generated by keyboard operation is comparatively low, however in the wind instrument, the breath flow is finely controlled by the player. Accordingly, after-touch data are frequently produced and a result, a number of after-touch data shall be supplied to the control apparatus. The control apparatus of the wind instrument needs a considerable time for processing data, when it processes all of received after-touched data as the control apparatus of the keyboard instrument processes all of the data. Therefore, a sound source of the wind instrument, in practice, shall generate musical tones with after-touch effect a little late after the playing operation of the player. In addition, not only the musical tones are generated a little late, but also the time lag of the musical tones varies depending on the variation in the speed at which after-touch data are produced. As a result, the performance effect is far from what the player expected.
The above described problems and/or drawbacks appear also in the control apparatus used only for an electronic wind instrument and have been waited to be solved.